ML19095A561

Response to IE Bulletin No. 76-05 Concerning Westinghouse Bfd Relay Failures

ML19095A561
Person / Time
Site:	Surry
Issue date:	05/14/1976
From:	Stallings C Virginia Electric & Power Co (VEPCO)
To:	Moseley N NRC/RGN-II
References
IEB-76-005, Serial No. 028
Download: ML19095A561 (2)

Text

VIRGINIA. ELECTRIC .AND POWER COMP.A.NY RICHMOND, VIRGINIA 232~~"~-,,_

May 14, 1976 ,, (f~_d_l_',)j~

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c~ Moseley, Director

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Mro Norman ~\-OIIS.<Hcr,, s~~1' No., 028 Office of Inspection and Enforcement . .P~/ALHzjlf u.. S$ Nuclear Regulatory Commission ~?;r~~v Region II~ Suite 818 ~ o c k e t Nos. 50-280 230 Peachtree Street, Northwest SQ ... 281.

Atlanta~ Georgia 30303 License Nos. DPRQ32 DPR-37

Dear Mr.,

Moseley:.

This is in response to IE Bulletin No. 76 .. 05 concerning Westinghouse BFD relay failures. We have received the Westinghouse service letter on BFD relays and have provided Westinghouse with all of the information requested thereinc The following is a list of our actions ~egarding the specific require-ments oft.he Westinghouse service letter.

I lo Normal DC bus voltage is maintained at 132 VDC. The Lead-Calcium  !

d batteries at Surry normally require no equilizing chargeso This l I

is true as long as individual cell voltages are maintained at 2o20 VDC. However, we have been in contact with the battery I manufacturer's representative and have taken steps to develop an equilizing charge procedure whereby DC bus voltage is not '

permitted to exceed 140 VDC. This procedure will also limit equilizing charge duration to 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />sa Therefore in the unusual

• event that an equilizing charge is required, the BFD (DC) relays will not be affected.

2$ Dropout time measurements have been made on all affected relays.

All relays but one had dropout times less than the 30 msec per-mitted. On_e relay on Unit No. One (1A13) had a dropout time of 34 msec. This relay provides a close signal to the Unit No.

One air ejector discharge to containment. Relay 1A13 will be replaced at the first Unit No. One shutdown following receipt of a replacement. The out of specification dropout time of relay 1..:\13 is not a problem since redundant relay 1B13 operated satis-factorily with a dropout time of 25 msec.

3. The ambient temperature of the relay racks housing BFD relays is maintained at about 84 F by the control and relay roan air conditioning system. Should any of these air conditioning units

.. fail, the station chilled water system can be used to provide.

• • the proper cooling. * *

• I

• :M:r,. Horman Co Moseley

• Page 2 l~o No equilizing battery charges have been performed since the relay I 5o dropout times were measured ..

This item is addressed in item number 1 above. I No further action is deemed necessary with regard to Westinghouse BFD relay*s at the Surry Power Station,.

Very truly yours, I !

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C,. M. Stallings Vice President-Power Supply II 1 and Production Operations t

j cc: NRC OFFICE OF INSPECTION AND ENFORCEMENT, Division of Reactor Inspection Programs Washington, DC 20555 l

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